'use strict';
function one_add_next_multiply_three(collection){
  let result = [];
  for(let i = 0;i<collection.length-1;i++){
    let m = (collection[i]+collection[i+1])*3;
    result.push(m);
    
  }
  
  console.log(result);
  return result;
}

one_add_next_multiply_three([1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21]);
module.exports = one_add_next_multiply_three;
